1. Field of the Invention
The present invention relates to high-frequency modules that transmit and receive a plurality of communication signals using a common antenna.
2. Description of the Related Art
There are various types of high-frequency modules among existing high-frequency modules that transmit and receive a plurality of signals having different frequencies using a common antenna. For example, a high-frequency module disclosed in Japanese Unexamined Patent Application Publication No. 2008-10995, includes a switching IC and a duplexer.
Here, a duplexer is a circuit device that separates a transmission signal and a reception signal that use different frequency bands in a single communication band. For example, a duplexer disclosed in Japanese Unexamined Patent Application Publication No. 2008-10995 is connected between an antenna input/output port (specifically, an antenna input/output port via a switch IC) and a pair of a transmission signal input port and a reception signal output port for a single communication band in a code division multiple access (CDMA) communication system. The duplexer transmits a transmission signal in the single communication band from the transmission signal input port to the antenna input/output port and transmits a reception signal in the single communication band from the antenna input/output port to the reception signal output port.
Currently, reductions in the sizes of high-frequency modules are required in accordance with reductions in the sizes of communication apparatuses. Thus, as disclosed in Japanese Unexamined Patent Application Publication No. 2008-10995, there may be cases in which a duplexer and a switch device need to be mounted so as to be close to each other.
However, since a high-power transmission signal is input to a duplexer, there may be a problem in that a portion of the transmission signal leaks from the duplexer to the switch device. In particular, when a transmission signal leaks to power system terminals for applying a driving voltage and a control voltage to the switch device and is superimposed on the driving voltage or the control voltage, the switch characteristics are degraded, which may lead to the degradation of the various characteristics of the high-frequency module.